1. Field of the Invention
The present invention relates to a method of and an apparatus for correcting unbalance of a rotatable member such as a rotor for an electric motor by adhering a correction material to the rotatable member or removing an unbalanced portion of the rotatable member.
2. Description of the Related Art:
There is known a dynamic balance correcting apparatus for correcting the unbalance of a rotatable member (such as a rotor for an electric motor or the like) by adhering a correction material (putty is usually used) such as known compositions disclosed in, for example, Japanese Patent Application Laid-Open No. 63-92639 to the rotatable member, or by removing an unbalanced portion of the rotatable member after a dynamic unbalanced state of the rotatable member is measured.
In each of the dynamic balance correcting apparatuses (disclosed in, for example, Japanese Patent Application Laid-Open No. 62-203535 and Japanese Utility Model Application Laid-Open No. 63-39655) for correcting the unbalance of a rotatable member by adhering a correction material to the rotatable member, an unbalanced state of the rotatable member (a so-called work) is measured by a measuring unit. Then, the position on the rotatable member at which correction is required and the quantity or mass of the correction material required to correct the unbalance are determined based on the result of measurement by the measuring unit. Further, based on the result of the determination, the rotatable member is positioned so that the position at which correction is required is oriented upward, and the correction material in a quantity corresponding to the amount of unbalance of the rotatable member to be corrected is delivered to the rotatable member from a delivery unit such as a nozzle, etc. so as to be adhered to the position on the rotatable member requiring correction.
In this type of conventional dynamic balance correcting apparatus, a positioning unit for positioning the rotatable member after completion of the measurement of the unbalanced state thereof and a delivery unit for delivering a correction material of a predetermined amount particularly made it necessary to carry out a so-called master alignment at regular intervals in order to adequately deal with time-dependent variations in the apparatus or changes in the work environment. In other words, the correction of each unit in the apparatus was carried out using a master work in such a manner that correction material in an accurate amount was adhered to the precise position on the rotatable member to be corrected.
However, master alignment requires a long period of time because extremely fine adjustment is required. Thus, the apparatus is deactivated over a long period of time during the interval in which the master alignment is carried out, and the operating efficiency of the equipment is greatly reduced.
In particular, even though master alignment is accurately carried out, the conventional dynamic balance correcting apparatus cannot sufficiently correct a fine error produced between each work actually fed to the apparatus for the correction of unbalance and the master work, a variation produced between each work, etc. Thus, an operator having adequate experience and skillfulness is necessary to the operation of the apparatus, in order to satisfactorily carry out the correction of the unbalance of each work.